1. Field of the Invention
The present invention relates to an information processing device and method, and particularly, an information processing device and method whereby the delay time of wavelet transformation processing and wavelet inverse transformation processing can be reduced, and costs can be reduced.
2. Description of the Related Art
An image compression method representative of known methods is the JPEG (Joint Photographic Experts Group) method that has been standardized by the ISO (International Standards Organization). This is known to provide excellent coded images and decoded images in the event that DCT (Discrete Cosine Transform) is used and a relatively great number of bits are appropriated.
In recent years, there has been much research performed on a method wherein images are divided into multiple bands (sub-bands) with filters called filter banks, wherein high-pass filters and low-pass filters are combined, and coding is performed for each band. Particularly, wavelet transformation coding is viewed as a new technology which is a likely candidate to replace DCT, since it does not have the problem that DCT has, i.e., marked block distortion at high compression rates.
International standardization of JPEG 2000 was completed January 2001. JPEG 2000 combines wavelet transformation and high-efficiency entropy coding (bit-plane based bit modeling and arithmetic encoding), and realizes marked improvements over JPEG with regard to coding efficiency.
Wavelet transformation processing (e.g., see Japanese Unexamined Patent Application Publication No. 10-283342) uses a technique wherein, basically, image data is taken as input which is subjected to horizontal direction filtering and vertical direction filtering, in which lowband components are hierarchically divided.
Wavelet inverse transformation processing for transforming the coefficient data (frequency components) transformed from image data by the wavelet transformation processing into the original image data performs processing for ultimately restoring an image while subjecting highband components and lowband components to synthesis filtering up to the lowermost division level from the uppermost division level.
With the wavelet inverse transformation processing, coefficient data in the middle of processing and ultimately obtained image data are held temporarily, but synthesis filtering is repeated recursively, so there is a need to perform writing and reading in/from buffer memory with high frequency.